Fibroids are benign growth in the uterus which are very common in women more than 35 years of age. The exact cause why some women develop these tumours is not known. Many factors such as genetic abnormalities, hormonal alterations, changes in growth factor (proteins formed in the body that direct the rate and extent of cell proliferation) expression, abnormalities in the vascular (blood vessel) system, and tissue response to injury are considered possible reasons which play a role in the development of fibroids.
Some factors which have been associated with the presence of fibroids include:
Family history: The exact gene responsible for fibroids is not known but women with a family history (mother, sisters with uterine fibroid) of fibroid are more likely to develop fibroids.
Race: This also appears to play a role as it has been noted that women of African descent are two to three times more likely to develop fibroids as compared to women of other races. Women of African ancestry tend to develop fibroids at a younger age (by their 20s) which is likely to be symptomatic from an early age in contrast to Caucasian women with fibroids, in whom symptoms usually start during the 30s and 40s.
Pregnancy and oral contraceptives: Both these factors decrease the chance that fibroids will develop. Fibroid does not develop in girls who have not reached puberty, and is rare in adolescent girls.
Hormonal influence: Oestrogen influences and tends to stimulate the growth of fibroids. Studies have noted that the size of fibroid increases during the first trimester of pregnancy, by up to 30% and then shrinks after the birth. After menopause the size of the fibroids may decrease (especially if the fibroid is small). But if you are on hormonal replacement therapy the symptoms may persist.
Other factors: Some other factors which probably increase the risk of developing fibroids are early start of menstrual period (menarche) prior to age 10,being overweight or obese, never having given birth to a child (called nulliparity), consumption of alcohol (particularly beer), uterine infections, and elevated blood pressure (hypertension).